Sites For Hydrogen Evolution Reaction Research Articles

Phosphorus Defect Mediated Electron Redistribution to Boost Anion Exchange Membrane‐Based Alkaline Seawater Electrolysis

AbstractIt is of essential importance to design bifunctional electrocatalysts with excellent performance for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in seawater splitting. Herein, an approach for manipulating electron redistribution in NiCoP treated by P defect (Pv) engineering (NiCoPv@NF) is presented, exhibiting excellent catalytic activities and stability toward HER/OER in alkaline seawater solution. The Pv reduces the surface electrooxidation reconfiguration energy barrier, making it easier to drive the local conversion of crystals to active oxy(hydroxide) in OER. In addition, the Ni site of NiCoPv and the Co site of NiCoOOH are the active sites for HER and OER processes, respectively. In situ generated PO43− adsorbed on the catalyst surface causes spatial repulsion, preventing Cl− corrosion in seawater electrolysis. The seawater AEM electrolyzer using NiCoPv@NF couple achieves excellent performance of high activity (2.43 V at 500 mA cm−2) and long‐term durability (500 mA cm−2 over 110 h). The working efficiency of AEM in 1.0 M KOH is as high as 77.0% at 100 mA cm−2 with the price of per GGE H2 as low as $ 0.87.

MoS2-CuCo2S4 nanosheets with a honeycomb structure formed on Ni foam: An efficient electrocatalyst for hydrogen evolution reaction

The physical, chemical, and electrocatalytic properties of conventional single-component electrocatalysts developed for the hydrogen evolution reaction (HER) no longer match the needs of many commercial applications. This necessitates for the creation of more sophisticated and effective electrocatalysts for the HER. In this study, MoS2-CuCo2S4 was loaded onto NF using a simple two-step hydrothermal method. In the resultant NF/MoS2-CuCo2S4 material, CuCo2S4 offers a lot of active sites to support vertically arranged MoS2 nanosheets, thereby decreasing their agglomeration. Moreover, the heterogeneous structure formed between CuCo2S4 and MoS2 facilitates charge transfer and exposes the active sites for HER, further improving the electrochemical hydrogen evolution performance of the heterostructured electrocatalyst. In a 1.0 M KOH solution, the synthesized NF/MoS2-CuCo2S4 nanosheet catalyst has outstanding electrocatalytic efficacy, with an overpotential as low as 67 mV at a current density of 10 mA·cm−2.

In Situ Reconstruction to Surface Sulfide Adsorbed Metal Scaffold for Enhanced Electrocatalytic Hydrogen Evolution Activity

AbstractTransition‐metal‐based compounds have been intensively explored as efficient electrocatalysts for hydrogen evolution reaction (HER). Feasible reconstruction to the real active sites, which is yet to be identified, endows the promotion of HER activity. Here, it is reported that the incoming S coordinates and anion vacancies prompt the structural reconstruction of S‐doped Co3O4 on carbon cloth (S‐Co3O4/CC) during HER. A list of in situ studies reveals that the real active sites for HER are the “metallic surface‐adparticles” system embracing metallic Co scaffold and the dilute coverage of S coordinated Coδ+. Reaction mechanism exploration illustrates that interfacial perimeters between the coverage of Co3S4 moieties and metallic Co considerably facilitate the adsorption of H*, improve the kinetics of water dissociation, and consequently promote HER activity. The exemplified sulfide‐mediated topotactic transformation strategy is extended to the preparation of S, Fe codoped Ni(OH)2 (S‐NiFe/CC) as a bifunctional electrocatalyst. The assembled anion exchange membrane water electrolyzer achieves a current density of 1.0 A cm−2 at 1.72 V, showing excellent capability in catalyzing overall water splitting at ampere level. This study, showing a feasible strategy that enables the facile reconstruction to identify active sites, would inspire the development of efficient electrocatalysts for HER and other electrochemical hydrogenation reaction.

Boosting Efficient Alkaline Hydrogen Evolution Reaction of CoFe-Layered Double Hydroxides Nanosheets via Co-Coordination Mechanism of W-Doping and Oxygen Defect Engineering.

While surface defects and heteroatom doping exhibit promising potential in augmenting the electrocatalytic hydrogen evolution reaction (HER), their performance remains unable to rival that of the costly Pt-based catalysts. Yet, the concurrent modification of catalysts by integrating both approaches stands as a promising strategy to effectively address the aforementioned limitation. In this work, tungsten dopants are introduced into self-supported CoFe-layered double hydroxides (LDH) on nickel foam using a hydrothermal method, and oxygen vacancies (Ov) are further introduced through calcination. The analysis results demonstrated that tungsten doping reduces the Ov formation energy of CoFeW-LDH. The Ov acted as oxophilic sites, facilitating water adsorption and dissociation, and reducing the barrier for cleaving HO─H bonds from 0.64 to 0.14eV. Additionally, Ov regulated the electronic structure of CoFeW-LDH to endow optimized hydrogen binding ability on tungsten atoms, thereby accelerating alkaline Volmer and Heyrovsky reaction kinetics. Specifically, the abundance of Ov induced a transition of tungsten from a six-coordinated to highly active four-coordinated structure, which becomes the active site for HER. Consequently, an ultra-low overpotential of 41mV at 10 mAcm-2 , and a low Tafel slope of 35mVdec-1 are achieved. These findings offer crucial insights for the design of efficient HER electrocatalysts.

Doping induced mixed polytypic interfaces of MoS2 for superior electrocatalytic hydrogen evolution

Metallic 1Tphase of MoS2 is desirable for accelerating electrochemical hydrogen generation from water due to its excellent electrical conductivity. However, it is challenging to synthesize stable 1T-MoS2 on a large scale using conventional chemical or physical routes. Here in, we report highly durable Mn-doping assisted in-plane 1T/2H mixed phases of MoS2 synthesized by a simple one-step hydrothermal method. The Mn-doping not only results in a favourable electronic modification in the host lattice but also in a structural evolution from 2H (trigonal prismatic) to 1T (octahedral) phase through sulfur-plane gliding with additional defects. The 1T/2H interfaces exhibit more active sites for hydrogen evolution reaction (HER) than its bulk 2H-counterpart. The developed electrode shows relatively low overpotential of 95 mV at a current density of 10 mA/cm2 and a low Tafel slope of 72 mV/dec in 0.5 M H2SO4. In addition, Density Functional Theory based calculations also support that Mn-doping in pristine 2H-MoS2 encourages a structural phase separation. Locally hybridized d-orbitals of Mn induce the formation of 2H/1T interfaces. It results in the delocalization of electrons, and thus facilitates the hydrogen adsorption and desorption process, better than the 2H phase.

High-Throughput Designed and Laser-Etched NiFeCrVTi High-Entropy Alloys with High Catalytic Activities and Corrosion Resistance for Hydrogen Evolution in Seawater.

Electrocatalytic hydrogen evolution from seawater through wind or solar energy is a cost-effective way to produce green hydrogen fuel. However, the lack of highly active and anti-corrosive electrocatalysts in seawater severely hinders the industrial application. Herein, a novel Ni1.1FeCr0.4V0.3Ti0.3 high-entropy alloy (HEA) is designed through high throughput computing and prepared via powder metallurgy with the surface treated by laser etching under different laser power. The laser-etched NiFeCrVTi high-entropy alloys exhibit a unique periodically ordered structure with multiple active centers and high porosity. The Ni-HEA-30 displays remarkable hydrogen evolution reaction (HER) performance with an overpotential of 55.9mV and a Tafel slope of 47.3mV dec-1 in seawater. Density functional theory (DFT) calculations are applied to identify the real active sites for HER on the HEA surface as the key factor for both proton and intermediate transformation, which also reveals that the Cr atom promotes the adsorption energy of water molecules, and the modulation of the electronic structure plays a crucial role in optimizing the hydrogen binding capabilities of the Ni atoms within the alloy. Additionally, the electrocatalyst displays high corrosion resistance in seawater, contributing to the good durability for hydrogen production. This work uncovers a new paradigm to develop novel electrocatalysts with superior reaction activity in seawater.

Tailoring the morphology of Mo2S3/MoP2 composite thin films via aerosol assisted chemical vapor deposition for enhanced hydrogen evolution reaction performance

In this study, we report on the fabrication of Mo2S3/MoP2 composite thin films using a single-step aerosol assisted chemical vapor deposition method from a single-source precursor solution of [(ƞ5-Cp)Mo(CO)2(S2P(SC6H4Me)2)] (1). Deposition times of 20, 30, and 40 min were used to obtain thin films with different morphologies. Our investigation found that the 30-minute thin film, which had a widely distributed grainy morphology, exhibited the highest electrocatalytic performance for hydrogen evolution reaction (HER) as determined by linear sweep voltammetry studies. This film required the lowest applied potential of 250 mV to generate a current density of 10 mAcm−2 with a low charge transport resistance of 715 Ω, despite having the lowest charge donor density of 5.52 × 1019 cm−3. We found that the unique morphology of this thin film enhanced electron mobility, resulting in superior HER performance with a Tafel slope of ∼123 mVdec−1 and a higher current charge density of 0.408 mAcm−2 due to increased active sites for HER. The Mo2S3/MoP2 heterostructure exhibited favourable band gaps of ∼2.2 and ∼2.7 eV, respectively, resulting in a synergistic effect that allowed for effective electron transfer. Our study concludes that different deposition durations produced composite thin films with altered morphologies that exhibit dissimilar electrochemical kinetics in HER.

Self‐integration exactly constructing oxygen‐modified MoNi alloys for efficient hydrogen evolution

AbstractIntroducing oxygen atoms into nickel‐based alloys is an effective strategy for constructing water dissociation sites for hydrogen evolution reaction (HER). However, controlling oxygen content to realize the best match of water dissociation and hydrogen adsorption is challenging. Herein, we exploit the self‐integration process of MoNi alloy in molten salts to introduce oxygen atoms, which ultimately leads to the localized generation of robust NiOxHy around the MoNi alloys. Interestingly, Mo is further doped into NiOxHy (Mo‐NiOxHy) to construct an effective active center for water dissociation due to the high mobility in ionic solutions. Owing to the covering and space confinement of molten salt, MoNi alloy is exactly decorated with Mo‐NiOxHy nanosheets. Both physical characterization and density functional theory calculation prove that the electron transport, water dissociation capability, and hydrogen adsorption of MoNi are finely tuned and benefited from the O and Mo doping, thus greatly expediting HER kinetics. Mo‐NiOxHy exhibits a much lower overpotential of 33 mV at 10 mV cm−2 in alkaline electrolyte, even superior to the Pt/C benchmark. Moreover, the final Mo‐NiOxHy requires a low overpotential of 57 mV at 10 mV cm−2 in acidic media. This enhancement is ascribed to the successful assembly of MoNi foam elicited by molten salt.

Constructing a Functionalized Electrocatalyst of a Transition Metal Chalcogenide on Accordion-Like MXene to Boost the Hydrogen Evolution Reaction.

MXenes exhibit unique layered structures and excellent electrical conductivity, and their multiple surface termination groups are favorable for hosting impressive performance for electrochemical reactions. Therefore, a two-dimensional (2D) layered MXene-based catalyst may become a novel high-efficiency electrocatalyst to replace traditional noble metal electrocatalysts. In this work, a transition metal chalcogenide (MoS2/CuS) and MXene are combined to prepare a 2D electrocatalyst (MoS2/CuS/MXene) for the hydrogen evolution reaction (HER). MXene exhibited a large specific surface area in the shape of an accordion, which was very beneficial for the growth of nanomaterials. CuS/MXene promoted electron transfer and improved the exposed active site for HER. The exposed MoS2 edges exhibited a high chemical adsorption capacity, which is conducive to HER. Electrochemical tests reveal that the MoS2/CuS/MXene electrocatalyst can reduce the charge transfer resistance toward the HER and increase active sites for HER, leading to enhancing the catalytic performance. The MoS2/CuS/MXene electrocatalyst affords an efficient HER with a low overpotential (115 mV@10 mA cm-2). This work offers a new idea to create layered transition metal chalcogenide- and MXene-based electrocatalysts for HER.

Phosphidation treatment of surfactant-tuned iron polyphthalocyanine grown in situ on nickel foam: An efficient bifunctional catalyst for overall water splitting

Developing robust electrocatalysts for overall water splitting is vital for industrial hydrogen production on a large scale. Herein, we obtain a bifunctional electrocatalyst NF@FePPc-s/p (where s represents surfactant and p stands for the phosphidation treatment) by phosphorization of surfactant (F127)-tuned iron polyphthalocyanine (FePPc) grown in situ on the nickel foam (NF) substrate. The as-obtained NF@FePPc-s/p exhibits the golden needle mushroom-like morphology, which is conducive to fully exposing the active sites and boosting the electron-transfer kinetics at the reaction interface. The physicochemical characterization and electrochemical measurements demonstrate that the active Fe2P and Ni2P phases formed during the phosphidation treatment are intrinsically active catalytic sites for hydrogen evolution reaction (HER), and the FeOOH formed from phase transformation of Fe2P during the oxygen evolution reaction (OER) process contributes a lot to enhancement of the OER activity. Furthermore, the electronic interaction between Fe and Ni further improves the electrocatalytic performances for both reactions. The optimized NF@FePPc-s/p catalyst exhibits remarkable OER (293 mV@100 mA cm−2) and HER (190 mV@100 mA cm−2) activities in 1.0 M KOH electrolyte. The water electrolyzer assembled with the NF@FePPc-s/p as the cathode and anode electrodes, respectively, only requires a low cell voltage of 1.743 V to obtain the current density of 100 mA cm−2 for overall water splitting, outperforming the precious NF@RuO2–Pt/C based electrolyzer (1.852 V).

Heterogeneous Cu incorporated into Ni6Fe2-LDH/rGO induces spin exchange interaction to enhance alkaline hydrogen evolution

The efficiency of hydrogen evolution reaction (HER) takes an important influence on electrochemical water electrolysis, yet it still delivers sluggish kinetics mainly due to the high kinetic energy barriers. Herein, Cu1Ni5Fe2-Layered double hydroxides/reduced graphene oxide (denoted as Cu1Ni5Fe2-LDHs/rGO) with heterogeneous Cu atoms incorporated into Ni6Fe2-LDHs/rGO is constructed through a hydrothermal method and doping strategy in this works, wherein the subtle lattice distortion is availably regulated and optimized by Cu2+ Jahn-Teller effect, offering more active sites for HER. As benefits of the subtle lattice distortion and the spin exchange interaction, Cu1Ni5Fe2-LDHs/rGO displays ferromagnetism at room temperature and shows superior alkaline HER properties with a relatively low overpotentials of 50 mV at 10 mA cm−2 in 1.0 M KOH. The low Tafel slope of 38 mV dec−1 implies Cu1Ni5Fe2-LDHs/rGO owns an ultra-fast HER kinetic. This study can offer a new strategy to construct high efficient HER catalysts based on transition metal NiFe-LDHs.

Analyzing electrocatalytically accessible sites for hydrogen evolution reaction in rGO doped copper cobalt sulphide

An important, yet difficult problem is the rational design and controlled production of an electrocatalyst for hydrogen evolution reaction (HER) using graphene-based bimetallic sulphide. Here, a novel electrocatalyst for HER was designed and created using a spherical-shaped structure grown on a graphene sheet with a conductive Cu-CoS2 support (rGO@CuCoS2). It takes advantage of the synergistic effect between the copper and cobalt sulphide phases, the naturally low resistance of the bimetal substrate, and the uniform spherical structure. With overpotentials of 84 mV at a current density of 10 mA cm−2 in alkaline electrolytes, the self-supported rGO@CuCoS2 composite catalyst demonstrates outstanding electrocatalytic activity for HER in an alkaline pH range, respectively. The created rGO@CuCoS2 catalyst impressively exhibits steady electrocatalytic activity and high durability in HER processes. The electrocatalytically accessible sites were also discovered to be 15.02 x 1017 sites at a 5 mV s−1 scan rate. This novel mix of methods is intended to offer a workable plan for the advancement of human energy and is promising much beyond the realm of water electrolysis.

Modulation of active site environment in an embedded CuOx@TiO2 photocatalyst for enhanced hydrogen evolution and CO2 reduction

Cocatalyst act as the active site usually plays an important role in both photocatalytic hydrogen evolution reaction (HER) and carbon dioxide reduction reaction (CO2RR). As the size, distribution, location, contact behavior with semiconductor etc. show significant effects for the activity. In this work, the active site environment (aggregation state of the active site of the cocatalyst) was modulated by locating the different amounts of CuOx nanoparticles (NPs) into the porous TiO2 (CuOx@TiO2), which was achieved by calcination of Cu@MIL-125 as the precursor. The composition, morphology, and chemical state of the catalyst were analyzed by a series of characterization methods. The results showed that the embedded CuOx NPs exhibited obviously better dispersion than the externally supported ones, especially at the high loading amount. Cu NPs totally transformed to CuO at the lower loading amount, while it transformed to CuOx with partial Cu (I) species existence at the higher loading amount. Photocatalytic reactions showed that the activity of CuOx@TiO2 was ∼ twice that of the traditional outside loading catalyst CuOx/TiO2 in both HER and CO2RR. The high HER activity was obtained at relatively lower loading capacity (0.200 wt%∼0.500 wt%), while CO2RR was the advantageous reaction at higher loading capacity (5.000∼15.000 wt%). Apparently, CuOx@TiO2 offered a quite different active site environment for the two type of reactions. The embedded structure can provide highly dispersed single active sites for HER at lower loading capacity, while it facilitates the formation of multi-electron environment under irradiation for CO2RR at higher loading capacity. The construction of an appropriate active center environment determines the occurrence of high-efficiency photocatalytic reactions.

Construction of multiple heterogeneous interfaces boosting alkaline hydrogen evolution

Alkaline hydrogen evolution reaction (HER) is suppressed by the water dissociation, leading to more sluggish kinetics than acidic HER. Developing multifunction catalysts via constructing heterogeneous interfaces is a feasible tactic to accelerate the alkaline HER. Herein, NiO coupled with Ni and MoxN (NMN) nanorods were prepared via a hydro-thermal synthesis combined with a thermal decomposition under ammonia atmosphere. The low crystalline NMN nanorods are rich in heterointerfaces, and have sufficient high active sites for HER. The synergistic effect between NiO and Ni-MoxN promotes the water dissociation the hydrogen adsorption, and the charge transfer, contributing to excellent alkaline HER activity. The overpotential on NMN is only 36 and 150 mV for the current density of 10 and 300 mA cm−2, respectively, and the Tafel slope is 48 mV/dec, demonstrating a superior performance for alkaline HER, which is even comparable to the commercial electrocatalysts.

Three-phase-boundary Pt in a self-supported MoPt2-MoNi4/Mo2C heterojunction electrocatalyst for highly efficient pH-universal hydrogen evolution reaction

Design of high-performance Pt-based electrocatalysts is significant for hydrogen production through water splitting at pH-universal conditions but still challenging. Herein, the MoPt2-MoNi4/Mo2C three-phase heterojunction is fabricated via simply pyrolyzing hydrothermally resultant Mo-Ni precursor with subsequent galvanic Pt replacement process. It exhibits remarkable and stable hydrogen evolution reaction (HER) performance with impressive mass activity and low overpotential of 53, 77 and 46 mV at the current density of 100 mA cm−2 in alkaline, neutral and acidic media, respectively. Density functional theory calculations illustrate that there are multiple types of Pt sites in the phase of MoPt2 in such three-phase heterojunction, while only the Pt atoms located in the three-phase boundary not only process optimal electronic structure modulated by MoNi4/Mo2C, but also act as highly-active sites for HER. Moreover, downshifted d-band center of Pt triggered by the construction of three-phase MoPt2-MoNi4/Mo2C heterojunction, which regulating the free energy of reactive intermediates sorption and thereby accelerating the entire HER process. This work provides some constructive suggestions to design highly efficient Pt-based heterostructured electrocatalysts towards HER.

Hydroxylated Polyoxometalate with Cu(II)- and Cu(I)-Aqua Complexes: A Bifunctional Catalyst for Electrocatalytic Water Splitting at Neutral pH.

A sole inorganic framework material [Li(H2O)4][{CuI(H2O)1.5} {CuII(H2O)3}2{WVI12O36(OH)6}]·N2·H2S·3H2O (1) consisting of a hydroxylated polyoxometalate (POM) anion, {WVI12O36(OH)6}6-, a mixed-valent Cu(II)- and Cu(I)-aqua cationic complex species, [{CuI(H2O)1.5}{CuII(H2O)3}2]5+, a Li(I)-aqua complex cation, and three solvent molecules, has been synthesized and structurally characterized. During its synthesis, the POM cluster anion gets functionalized with six hydroxyl groups, i.e., six WVI-OH groups per cluster unit. Moreover, structural and spectral analyses have shown the presence of H2S and N2 molecules in the concerned crystal lattice, formed from "sulfate-reducing ammonium oxidation (SRAO)". Compound 1 functions as a bifunctional electrocatalyst exhibiting oxygen evolution reaction (OER) by water oxidation and hydrogen evolution reaction (HER) by water reduction at the neutral pH. We could identify that the hydroxylated POM anion and copper-aqua complex cations are the functional sites for HER and OER, respectively. The overpotential, required to achieve a current density of 1 mA/cm2 in the case of HER (water reduction), is found to be 443 mV with a Faradaic efficiency of 84% and a turnover frequency of 4.66 s-1. In the case of OER (water oxidation), the overpotential needed to achieve a current density of 1 mA/cm2 is obtained to be 418 mV with a Faradaic efficiency of 80% and turnover frequency of 2.81 s-1. Diverse electrochemical controlled experiments have been performed to conclude that the title POM-based material functions as a true bifunctional catalyst for electrocatalytic HER as well as OER at the neutral pH without catalyst reconstruction.

Exploring the Role of Multi-Catalytic Sites in an Amorphous Co–W–B Electrocatalyst for Hydrogen and Oxygen Evolution Reactions

Amorphous materials are used in multitude of catalytic applications, including electrocatalytic water-splitting. Identification and investigation of active sites in amorphous catalysts are rarely reported, mainly owing to the complexity of the systems. Herein, we report an amorphous bifunctional Co–W–B electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The optimized Co–W–B catalyst showed promising overpotential values of 97 mV (HER) and 292 mV (OER), respectively, to achieve 10 mA cm–2 in 1 M KOH, with good stability. The promoting effect of W in Co–B was investigated experimentally, while computational tools were used to identify all the possible catalytic sites in an amorphous Co–W–B model and classify the most preferred sites for HER and OER. The presence of multi-catalytic sites with specific selectivity toward HER and OER was observed, which explained the bifunctional activity of Co–W–B. This study will foster better understanding of the origin of catalytic activity in similar amorphous systems.

Green fabrication of nanostructured Ni(OH)2/Ni/Carbon felt electrodes with water-containing deep eutectic solvent for enhanced water electrolysis performance

To produce green hydrogen, the development of high-performance, environmentally friendly, and cost-effective electrocatalysts for efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is imperative. This study explores the potential application of water-containing deep eutectic solvents (DESs) in the synthesis of nanostructured electrocatalysts for water electrolysis. Ni(OH)2/Ni/carbon felt (CF) composite electrodes are developed via one-step electrodeposition in a water-containing choline chloride/urea DES as a green reaction medium. Heterostructured Ni(OH)2/Ni nanosheets are formed and uniformly deposited on the CF substrate with the addition of 10 wt% water to DES (CU10W), which increases active sites for HER and OER. The initial confinement of water molecules by the DES is found to be crucial in forming the hierarchical structure of the electrocatalysts. Notably, the CU10W electrode exhibits excellent bifunctional activity toward HER and OER, with reduced overpotentials of 192 and 564 mV, respectively, at 100 mA cm−2. This renders the CU10W electrode-based electrolysis system stable with a reduced cell voltage of 1.69 V and a high Faradaic efficiency of over 99% for the HER. The augmented electrochemical active surface area and reduced charge transfer resistance of the CU10W electrode account for the improved HER/OER performance associated with the special hierarchical Ni(OH)2/Ni nanostructure.

Modulation of electronic density states of carbon atom via multifaceted Cu doped Co2P particle for robust and efficient electrocatalytic hydrogen evolution reaction in aqueous acidic medium

Development of Pt free catalyst for hydrogen evolution reaction (HER) having both superb efficiency and sound stability is a key challenge in the field of alternate fuel production. Herein, we have reported Cu doped multifaceted Co2P particles incorporated on expanded graphite synthesized via solvothermal method, and studied its catalytic activity. The composite catalyzes the evolution of H2 efficiently with a potential value 81 mV to achieve the benchmark current density of 10 mA cm-2 and a Tafel slope value of 113 mV dec‑1 coupled with a remarkable long-term stability for 21.6 h. Our experimental analysis provides strong evidence that the multifaceted Cu doped Co2P could work in concert with carbon atoms of the expanded graphite (EG) that leads in the changing of the energy states of nearby carbon atoms of the metal phosphide particle which is also in well agreement of our theoretical calculation. The lower contact electrical resistance of EG have significant impact in endowing fast electron transfer to the catalytic active sites and the aid of catalytic performance. The specific morphology of the catalyst hints at increased surface area and overall exposed active sites to bestow the catalytic performance. The study suggests that the energetically modulated carbon atoms can act as a fine active site for HER.

Creating Dual Active Sites in Conductive Metal‐Organic Frameworks for Efficient Water Splitting

AbstractThe achievement of bifunctional metal‐organic frameworks (MOFs) remains a huge challenge due to their lack of dual active sites. Herein, dual sites in the Co‐catecholate (Co‐CAT) are created through Ru, Ir, or Rh doping for overall water splitting. Among them, RuCo‐CAT exhibits excellent bifunctional activities, outperforming benchmarked Pt/C for the hydrogen evolution reaction (HER) and RuO2 for the oxygen evolution reaction (OER). The theoretical calculations demonstrate that the doped Ru atoms with optimal absorption energy for the hydrogen intermediate and the Co centers with a reduced energy barrier for the rate‐determining step are the active sites for HER and OER, respectively. Furthermore, the incorporation of Ru atoms can improve the electrical conductivity and capacity of water adsorption of Co‐CAT greatly, synergistically improving the bifunctional activity. This strategy for engineering dual active sites offers novel insights into designing bifunctional MOFs for overall water splitting.